"In determining whether a conflict exists the ABC takes into account how it might be managed and considers both the nature of the external work and the work within the organisation.”

Not all speakers have had links to the ABC. And figures suggest fees for guest speakers paid for by the public service do not vary greatly.

Communications expert Jeffrey Cole was brought in as a keynote speaker for Australian Communications and Media Authority's RadComms 2013 conference at a cost of $12,803. The ACMA has confirmed this was only for travel costs and Mr Cole did not charge a fee.

In 2011 the National Archives of Australia paid $11,462 to have business advisor Bernard Salt record a video address to be used in the training of senior staff, which the archives saw as a valuable tool in its long-term corporate planning.

The Defence contract prompted outrage from a union representing workers as it was signed in the midst of tough bargaining negotiations with staff offered a less than 0.9 per cent a year pay rise while annual inflation runs at 3 per cent.